Method for screening transgenic plants for anthelmintic activity
The present invention provides DNA constructs, transgenic plants containing such constructs, and methods of making the plants. The DNA constructs encode a polypeptide that when expressed results in the production of fatty acid compounds having anthelmintic activity. Transgenic plants expressing such a polypeptide can exhibit enhanced resistance to plant parasitic nematodes, particularly when expressed in vegetative tissues.
1. A method of screening a transgenic plant for anthelmintic activity, comprising contacting a transgenic plant, wherein said transgenic plant contains at least one DNA construct, said construct comprising:
a) a nucleic acid encoding a polypeptide catalyzes the conversion of a substrate to a C16, C18, or C20 monounsaturated fatty acid product selected from the group consisting of:
wherein X is hydrogen, CoA, glycerol, a monoglyceride, a diglyceride, ACP, methyl, Na+, phosphatidylcholine, or phosphatidylethanolamine, wherein both R1 and R2 are hydroxyl, one of R1 and R2 is hydroxyl and the other is hydrogen, or one of R1 and R2 is keto and the other is hydrogen, and wherein R3 is C2, C4, or C6 alkyl; and
wherein X is hydrogen, CoA, glycerol, a monoglyceride, a diglyceride, ACP, methyl, Na+, phosphatidylcholine, or phosphatidylethanolamine, and wherein R3 is C2, C4, or C6 alkyl; and
(b) a regulatory element operably linked to said nucleic acid encoding said polypeptide, wherein said regulatory element confers expression in a vegetative tissue of said plant,
with a plurality of nematodes under conditions effective to determine whether or not said plant has anthelmintic activity.
2. The method of claim 1 , wherein said nematodes are contacted with one or more roots of said transgenic plant.
3. A method of screening a transgenic plant for anthelmintic activity, comprising contacting tissue from a transgenic plant, wherein the transgenic plant contains at least one DNA construct, said construct comprising:
a) a nucleic acid encoding a polypeptide catalyses the conversion of a substrate to a C16, C18, or C20 monounsaturated fatty acid product selected from the group consisting of:
wherein X is hydrogen, CoA, glycerol, a monoglyceride, a diglyceride, ACP, methyl, Na+, phosphatidylcholine, or phosphatidylethanolamine, wherein both R1 and R2 are hydroxyl, one of R1 and R2 is hydroxyl and the other is hydrogen, or one of R1 and R2 is keto and the other is hydrogen, and wherein R3 is C2, C4, or C6 alkyl; and
wherein X is hydrogen, CoA, glycerol, a monoglyceride, a diglyceride, ACP, methyl, Na+, phosphatidylcholine, or phosphatidylethanolamine, and wherein R3 is C2, C4, or C6 alkyl; and
(b) a regulatory element operably linked to said nucleic acid encoding said polypeptide, wherein said regulatory element confers expression in a vegetative tissue of said plant,
with a plurality of nematodes under conditions effective to determine whether or not said plant tissue has anthelmintic activity.
4. The method of claim 3 , wherein said tissue is root tissue.
5. The method of claim 1 or 3 , wherein said plant is selected from the group consisting of tobacco, tomato, soybean, corn, cotton, rice, wheat, banana, carrot, potato, strawberry and turf grass.
6. The method of claim 1 or 3 , wherein said DNA construct further comprises a nucleic acid encoding a PDAT, DAGAT, lipase, FAD2, or FAD3 polypeptide operably linked to a at least one regulatory element that confers expression in vegetative tissue of said plant.
7. The method of claim 1 or 3 , wherein said anthelmintic activity comprises an increase in nematode-killing activity as compared to a corresponding plant lacking said nucleic acid encoding said polypeptide.
8. The method of claim 1 or 3 , wherein said anthelmintic activity comprises a reduction in nematode development as compared to a corresponding plant lacking said nucleic acid encoding said polypeptide.
9. The method of claim 1 or 3 , wherein said anthelmintic activity comprises an increase in nematode sterility as compared to a plant lacking said nucleic acid encoding said polypeptide.
10. The method of claim 1 , wherein said anthelmintic activity comprises a reduction in the ability of a nematode to infect said plant as compared to a plant lacking said nucleic acid encoding said polypeptide.
11. The method of claim 3 , wherein said anthelmintic activity comprises a reduction in the ability of a nematode to infect said plant tissue as compared to a plant lacking said nucleic acid encoding said polypeptide.
12. The method of claim 1 , wherein said anthelmintic activity comprises a reduction in the ability of a nematode to reproduce within said plant as compared to a plant lacking said nucleic acid encoding said polypeptide.
13. The method of claim 3 , wherein said anthelmintic activity comprises a reduction in the ability of a nematode to reproduce within said plant tissue as compared to a plant lacking said nucleic acid encoding said polypeptide.
14. The method of claim 1 or 3 , wherein said anthelmintic activity comprises a reduction in the number of root galls as compared to a plant lacking said nucleic acid encoding said polypeptide.
15. The method of claim 1 or 3 , wherein said nematodes are selected from the group consisting of Meloidogyne spp., Heterodera spp., Pratylenchus spp., Paratrichodorus spp., Tylenchorhychys spp., Globodera spp., Rotylenchulus spp., Hoplolaimus spp., Belonolaimus spp., Longidorus spp., Ditylenchus spp., Xiphinema spp., Dolichodorus spp., Helicotylenchus spp., Radopholus spp., Hirschmanniella spp., and Trichodorus spp.